Muscimol, beta-endorphin and apomorphine reduce the turnover rate of acetylcholine in hippocampus by an action in septum. Bicuculline injected intraseptally will reverse these effects suggesting the presence of septal GABAergic interneurons. Intraseptal (lateral) kainate reduces septal dopamine stimulated adenylate-cyclase and glutamic acid decarboxylase but not hippocampal choline acetyltransferase. Intrahippocampal kainate destroys hippocampal pyramidal cells and reduces high affinity glutamate uptake in septum without affecting hippocampal turnover rate of acetylcholine. Decortication reduces turnover rates of acetylcholine and gamma-aminobutyric acid in striatum. Intrastriatal kainate also reduces acetylcholine turnover in striatum. These data suggest that the cortical input to the striatum involves excitatory glutamatergic neurons modulating both GABAergic and cholinergic functions.